Accumulator



M. W. HUBER Jan. 11,1944.

ACCUMULATOQR Filed Dec.

ZSnnentor Macch ew W. Huber Clitornegs Patented Jan. 11, 1944 UNITED ST res errur OFFICE 2,339,076 ACCUMULATOR Matthew W. Huber, Chicago, 111., assignor to Hydraulic Controls, Inc.,

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a corporation of Illi- Application December 2, 1942,'Serial Nor 167,630

4 Claims. ,(i'Jl. 138-30) This invention relates to hydraulic accumulators of the gas cushion type.

On a number of devices, notably military tanks and airplanes, there is need for high pressure,

light-weight accumulators for use as a part of hydraulic systems. For various reasons it is necessary to use a diaphragm which separates the hydraulic liquid from the cushioning gas. These diaphragms are customarily made of a syn thetic rubber-like material, not harmfully affected by hydraulic liquid (usually oil). Attempts to construct the shell in sections which are separable to permit replacement of the diaphragm have not been successful because of limitations imposed by the very high pressures used in the accumulators. Consequently recourse has been had to a welded construction which was expensiv both as to initial cost, and because the shell could not be salvaged if the diaphragm failed.

The present invention produces a type of joint which can be made quite inexpensively, and which is sufliciently strong to resist the high pressures encountered.

In the drawing a successful embodiment of the invention is illustrated.

Fig. l is a view, half in vertical section and half in elevation, of the accumulator, omitting certain conventional parts.

Fig. 2 is a view showing the two parts of the accumulator shell slightly separated, and indicating the position of the diaphragm prior to clamping.

Fig. 3 is a detail of one of the tapered plugs used to connect the two portions of the accumulator.

The shell of the accumulator is approximately spherical in contour so as to be stable under internal pressure and is made of pressed steel of substantial thickness. It comprises two halves 6 and 1 which telescope one into the other and thus form a lap joint. The form of the overlapping portions is worked out, as indicated in the drawing, to preserve as nearly as possible the continuous spherical contour of the shell. In the embodiment illustrated, the lower section I has a cylindrical margin which overlaps a similar but smaller cylindrical margin on the upper section The lower section 1 carries a steel annulus 8 which inside and welded to the section l as indicated at 9. This annulus fits closely within the cylindrlcal margin of the upper shell-half 6. However, between the weld 9 and the cylindrical portion of the annulus there is an inward annular bulg l t which forms a seat for the diaphragm hereafter described.

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Similarly, the upper half 6 of the shell carries an external annulus l2 which is cylindrical at its lower margin, so as to fit over the outside of the cylindrical margin of the lower shell half I. The annulus I2 is welded to the upper she'll portion 5, as indicated at l3. Thus, each half of the shell has two marginal rims which inter-fit. To connect them, use is made of tapered plugs M. The use of twelve such plugs is indicated in the drawing. Theseplugs closely fit tapered holes formed in the overlapping portions. At their outer ends the plugs are enlarged and threaded, as indicated at [5, so as to screw into threaded plates I 3 formed separately from the annulus l 2 and spotwelded thereto'as indicated at IT. It will be observed that the tapered plugs are in triple shear and thus produce a very strong connection.

The diaphragm is generally indicated at 8 and is of the slack or pleated type. The plates I 9, 2| which are connected through the center of the diaphragm, are provided to prevent the center of the diaphragm from blinding the hydraulic liquid connection 22.

The threaded connection 23 receives the charging valve for the gas cushion so that the space above the diaphragm may be charged with gas at high pressure. Th valve is not illustrated.

The space below the diaphragm is the liquid space. In normal operation, the diaphragm simply floats between the two pressure fluids and is not subject to any pronounced leakage tendency. However, its marginal portion must seal the joint between the two halves 6 and 1 against a hydraulic pressure of several thousand pounds per square inch. To accomplish this result, a third annulus 24 is welded at 26 to the interior of the upper half 6. It fits closely against the upper margin of the annulus 8 and has a concave recess on its outer face so located that it and the bulge l l already mentioned, form a confining space for the bulbous annular rim 2 5 which surrounds the diaphragm [8. This rim is so dimensioned that when the diaphragm is positioned, as indicated in Fig. 2, it must be stretched slightly and thus becomes self-retaining. After the diaphragm is in place, a indicated in Fig. 2, the two parts are pushed together and the tapered plugs are inserted. If the holes do not align perfectly the plug will force the two sections into their proper final position. The plugs are socketed to receive a wrench.

The importance of a close fit between the annulus 24 and the margin of the annulus l I will now be apparent. The rim 25 of the diaphragm is closely confined, and placed under compression so as to form an effective seal against outleakage of the hydraulic liquid.

The invention produces a strong shell which is stable in form and tightly sealed. It has substantial advantages over prior art separable shell constructions, being much lighter and stronger. In the prior art, two arrangements have been proposed. One is a simple bolted flange which is very heavy because thick flanges and heavy bolts are required. In the other proposed arrangement, the two sections are threaded together, a construction which requires massive threads and the use of a power wrench to assemble and dismount the parts.

The use of tapered shear pins gives the necessary draw to compress the gasket. The use of the margin of the diaphragm as the gasket simplifies the construction.

What is claimed is:

1. ,An accumulator comprising a shell formed of two separable portions having interleaved mating cylindrical joint forming portions; taper pins extending through some of said interleaved portions so as to be stressed in multiple :shear when the shell is under pressure; means serving to seat said pins; and a gasket sealing the oint at said interleaved portions and arranged to be compressed by the draw produced by the seating of the taper pins.

2. An accumulator comprising a shell formed of two separable portions having interleaved mating cylindrical joint forming portions; taper pins extending through some of said interleaved portions so as to be stressed in multiple shear when the hell is under pressure; means serving to seat said pins; and a flexible diaphragm separating the interior of said shell into two distinct spaces and having a marginal bead which serves as a gasket to seal the joint between said interleaved portions, said bead being arranged to be compressed by the draw produced by seating the taper pins.

3. An accumulator comprising a shell formed of two separable portions each having at least two interleaved mating cylindrical rims; taper pins extending through said rims and stressed in triple shear when the shell is under pressure; means forming a gasket retainer overlying the inner ends of aid pins and sealed to one portion of the shell; a gasket interposed between the retainer and the other portion of the s e and producing a seal between the same and also with the inner ends of the pins; and threaded means for seating the pins.

l. An accumulator comprising a shell formed of two separable portions each having at least two interleaved mating cylindrical rims; taper pins extending through said rims and stressed in triple shear when the shell is under pre sure; means forming a gasket retainer overlying the inner ends of said pins and sealed to one portion of the shell; a diaphragm having a marginal gasket forming pertion interposed between the retainer and the other portionof the shell and producing a seal between the ame and also with the inner ends of the pins; and threaded means for seating the pins.

MATTHEW W. HUBER. 

